Various terms are defined in the following specification. For convenience, a Glossary of terms is provided herein, immediately preceding the claims.
Laws such as the Clean Air Act (1990) and the Energy Policy Act (1992), which mandate the purchase of alternative fueled vehicles (AFVs), have spurred several serious business initiatives to develop natural gas vehicles (NGVs). Although these laws were motivated by air quality issues, they have created economic incentives that have spurred real activity in implementing NGVs. NGVs currently hold the most competitive potential alternative to gasoline-powered vehicles because of the inherent clean-burning characteristics of natural gas.
Compressed natural gas (CNG) technology is a candidate for the implementation of NGV-type AFVs. In current CNG technology, gaseous (natural gas) fuel is stored at very high pressures of about 20.7 MPa to 24.8 MPa (3000-3600 psia) and typically in containers made from X-65 steels, aluminum, or from carbon or glass fiber composites. Many publications and issued patents discuss CNG technologies. For example, see “Finally: A Lightweight CNG System”, published in the April/May 1984 edition of School Bus Fleet, WO 95/32874, U.S. Pat. Nos. 5,330,031, and 5,458,258. Despite these publications and issued patents, there are major shortcomings of current CNG technology that have limited its successful deployment: short vehicle driving range (due to low energy storage density of CNG); the weight and high cost of on-board (and typically non-conformable) fuel storage containers; low fuel efficiency due to the weight of fuel storage containers; and low load-carrying capacity of the vehicle, corresponding to the incremental weight of the fuel storage tanks.
A need exists for fuel storage and delivery systems capable of economically storing CNG fuel and delivering CNG fuel on demand for combustion in an engine. Further, a need exists for such fuel storage and delivery systems that allow for longer vehicle driving ranges, as well as lighter and less expensive storage containers than are provided by current CNG technologies.
Consequently, the primary object of the present invention is to provide improved fuel storage and delivery systems suitable for storing CNG fuel and delivering CNG fuel on demand for combustion in an engine.